Invasive probes are used in a variety of medical procedures, such as cardiac electrophysiological (EP) mapping and ablation. Some probes have tips that are pre-shaped to the desired form. For example, U.S. Pat. No. 5,617,854, whose disclosure is incorporated herein by reference, describes a pre-shaped cardiac catheter for mapping and selective ablation of a portion of cardiac circuitry. The catheter includes a pre-shaped first curved portion for positioning around the ostium of coronary sinus and a second curved portion for maintaining the first curved portion in its desired position. A catheter assembly, including a guide-wire and a preshaped catheter, is inserted to a location proximal the atrium. As the guide-wire is withdrawn from within the catheter, the catheter assumes its preshaped form at the target location. Alternatively, a catheter assembly, with or without a guide-wire, may be introduced to the target ablation site via a catheter sheath. The catheter includes an array of spaced apart electrodes on at least a portion of the catheter.
U.S. Patent Application Publication 2007/0049924, whose disclosure is incorporated herein by reference, describes an ablation catheter for setting a lesion. The catheter contains an ablation element that can be slid out of a catheter sleeve and has a looped section which, when the element is slid out, self-expands into an automatically or manually imposed pre-specified shape corresponding to the actual shape of the area of tissue requiring to be ablated.